This is a competitive renewal of grant "Genomic Scanning for Epigenetic and Genetic alterations in Head and neck cancer". The previous grant has been successfully completed and resulted in a wealth of data describing altered DMA methylation and DMA amplification in head and neck squamous cell carcinoma (HNSCC). One of the novel genes (transcription factor 21 orTCF21), identified on chromosome 6q23-24, a region frequently lost in HNSCC, as well as other malignancies has tumor suppressor function, as well as metastasis suppressing activity. TCF21 is a frequent target for altered DMA methylation in human tumors and is transcriptionally silenced by DMA methylation. We provide preliminary data supporting our hypothesis that TCF21 is a novel tumor/metastasis suppressor gene. To address this hypothesis, we propose three specific aims. (1) In aim 1 we will investigate expression patterns of TCF21 and possible alternative splice forms in various normal tissues and cancer cell lines and evaluate in detail how DMA methylation contributes to DMA silencing. We will next evaluate the mutational spectrum of TCF21 in HNSCC and lung cancer to determine the importance of TCF21 silencing in each tumor type. (2) In aim 2 we propose experiments that will help to understand how TCF21 contributes to tumorgenesis and identify binding partners and target genes specific for different tissues using a combination of expression array, ChIP, yeast two hybrid and luciferase assays. (3) In aim 3 we will utilize mouse models to further investigate the role of TCF21. We are planning nude mouse tumorigenicity and metastasis assays, we are proposing a carcinogenesis experiment with Tcf21 heterozygous knock out mice;and will investigate Tcf21 and downstream targets in a mouse model for oral cavity carcinogenesis and lung carcinogenesis.